Microwave accelerated synthesis of nanosized calcium deficient hydroxyapatite

摘要

Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca_(10-x)(HPO_4)_x(PO_4)_(6-x)(OH)_(2-x)) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA has the characteristic HPO_4~(2-) vibration band at 875 cm~(-1) in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (β-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600℃.